Method for electrostatically coating synthetic resin moldings

ABSTRACT

WHEREIN: R is a hydrocarbon radical having seven to 21 carbon atoms, R&#39;&#39; is selected from the group consisting of H and -CH3, Z is selected from the group consisting of -O- and -NH-, M is a metal ion selected from the group consisting of Mg, Ca, Zn, Ba and Fe, R1 is selected from the group consisting of -R2COO-, -R2SO3- and -R2OSO3- (where R2 is selected from the group consisting of CH2-, -C2H4- or -C3H6-), n is a number from 0 to 3.   Electrostatic coating of synthetic resin moldings is simplified by mixing in the synthetic resin from 0.1-5 wt. % of an amphoteric surface active agent of the formula

United States Patent Marumo et al.

[ 1 June 20, 1972 [54] METHOD FOR ELECTROSTATICALLY COATING SYNTHETICRESIN MOLDINGS [72] Inventors: Hideo Marumo; Morio Ninomiya, both ofTokyo; Shinro Watanabe, lchikawa, all of Japan [73] Assignee: Lion FatOil Co., Ltd., Tokyo, Japan [22] Filed: Dec. 21, 1970 [2]] Appl. No.:100,346

Related US. Application Data [63] Continuation of Ser. No. 687,993, Dec.5, 1967, abandoned.

[30] Foreign Application Priority Data Dec. 8, 1966 Japan ..4l/8007O[52] U.S. Cl ..260/80.7, 260/775 D, 260/855 R,

260/928 A, 260/935 A, 260/93.7, 260/949 GR, ll7/93.4 NC, ll7/138.8 E,ll7/l38.8 R, 117/1388 UA, 204/192 [51] Int. Cl. ..C08f 1/88 [58] Fieldof Search 260/775 D, 80.7, 85.5 R, 92.8 A, 260/937, 93.5 A, 94.9 GB

[56] References Cited UNlTED STATES PATENTS 2,528,378 10/1950 Mannheimer..260/309.6 2,781,354 2/1957 Mannheimer.. ....260/309.6 2,982,651 5/1961Mackey ....260/309.6 3,316,232 4/1967 McGann ..260/93.7

OTHER PUBLlCATlONS Encyc. of Polymer Science and Technology, 2, 204-213, Interscience, New York, 1965 Encyc. of Chemical Technology, 3, 797-799, lnterscience, New York 1964). Journal of the Chemical Society ofJapan, 68, No. l l, 2202- 2286(Nov. 1965). Synthesis and Application ofSurface Active Agents, 176- 177, (July 31,1966).

Primary E.\'aminerJoseph L. Schofer Assistant E.\'aminer-Stanford M.Levin AuorneyWoodhams, Blanchard & Flynn [5 7] ABSTRACT Electrostaticcoating of synthetic resin moldings is simplified by mixing in thesynthetic resin from 0.1-5 wt. 71 of an amphoteric surface active agentof the formula 6 Claims, No Drawings METHOD FOR ELECTROSTATICALLYCOATING SYNTHETIC RESIN MOLDINGS CROSS-REFERENCE TO RELATED APPLICATIONThis application is a continuation of our copending application, Ser.No. 687 993, filed Dec. 5, I967 and now abandoned.

BACKGROUND OF THE INVENTION The present invention is concerned with animproved electrostatic coating method which permits one to performeasily an electrostatic coating on various synthetic resins rangingwidely in type by a simplified coating process due to the fact that ametal salt of an amphoteric surface active agent is mixed with thesynthetic resin which is to be coated.

DESCRIPTION OF THE PRIOR ART With the conventional methods forconducting electrostatic coating of synthetic resins, it has beenimpossible to obtain films of coatings having satisfactory adhesivenessunless the coating is performed after the resin moldings are subjectedto the so-called precoating treatment which includes a series oftreatments such as a dewaxing treatment, a washing treatment, anair-drying treatment (at 60 C 70 C. for 20 minutes), a surfaceactivating treatment (priming treatment) and an air-drying treatment, inthat order. Also, the synthetic resins employed in such electrostaticcoating methods of the prior art usually have beenacrylonitriIe-butadiene-styrene copolymers. Because of the reason thatin the past it has been difficult to conduct coating of resins otherthan the abovementioned copolymers, it has been the practice, in lieu ofcoating, to mix resins other than said copolymers with pigments by theemployment of kneading techniques, for the purpose of improving theluster of the resins.

Despite the extensive strong demand in the past for simplification ofthe aforesaid completed process of precoating treatment which has beennecessary for the electrostatic coating of synthetic resins in the past,and despite the keen demand for the development of a method whichpermits the electrostatic coating to be performed also on those resinswhich could not be coated electrostatically, there has been made, asyet, no effective and satisfactory proposal.

SUMMARY OF THE INVENTION DESCRIPTION OF THE PREFERRED EMBODIMENTS I Thepresent invention provides a quite simple method having a greatadvantage, such as described above, by the employment of a material, asthe article for being coated, which is composed of a synthetic resinmixed, by kneading, with a metal salt consisting of an amphotericsurface active agent expressed by the general formula:

| NR, M

IIO

wherein:

R is a hydrocarbon radical having seven to 21 carbon atoms, R isselected from the group consisting of H and --CH;,, 2 is selected fromthe group consisting of 0--and NH M is a metal ion selected from thegroup consisting of Mg,

Ca, Zn, Ba and Fe,

R is selected from the group consisting of R COO,

R SO -and R OSO Where R is selected from the group consisting of -CH CH-- or C;,H,,),

n is a number from 0 to 3.

In the present invention, it is desirable to use a material, as thearticle to be coated, which is composed of a synthetic resin and a metalsalt consisting of a surface active agent expressed by the foregoinggeneral formula, said metal salt being mixed, by kneading, with saidresin in an amount ranging from 0.1 to 5.0 percent by weight, preferablyin the range of from 0.5 to 2.0 percent by weight, of the weight of saidresin. Since the synthetic resin having undergone said treatment has asurface conductivity, it is possible to omit the surface activatingtreatment before performing electrostatic coating, and besides, acoating which is excellent in adhesiveness can be obtained.

As has been described, the present invention represents an improvedcoating method which not only makes it easy to perform electrostaticcoating of resins by only subjecting said resins to a very simpletreatment, but also enables one to carry out electrostatic coating onvarious types of resins which have been considered difficult to becoated electrostatically.

The hydrocarbon radicals having C -C which are contained in thecompounds used in the present invention and expressed by the aforesaidgeneral formula include, for example, heptyl, octyl, nonyl, decyl,undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl,heptadecyl, l-methyl hexyl, l-methyl heptyl, l-methyl octyl, lmethylnonyl, l-methyl decyl, lmethyl undecyl, l-methyl dodecyl, l-methyltridecyl, l-methyl tetradecyl, l-methyl pentadecyl, l-methyl hexadecyl,l-methyl heptadecyl, l-methyl octadecyl, l, l dimethyl pentyl,l,l-dimethyl hexyl, l,l-dimethyl heptyl, l,ldimethyl octyl, 1,1-dimethylnonyl, l,l-dimethyl decyl, 1,1 dimethyl undecyl, l,l-dimethyl dodecyl,l,l-dimethyl tridecyl, 1,1-dimethyl tetradecyl, 1,1-dimethyl pentadecyl,l,l-dimethyl hexadecyl, l,l-dimethyl heptadecyl, l,ldimethyl octadecyland 8-heptadeceneyL The metal moeity of the slat is a member of thegroup consisting of the magnesium ion, the calcium ion, the zinc ion,the barium ion and the ferrous ion.

EXAMPLE The following compounds:

( NCH2 nHas CHzCOO (2) %NCH2 n aa N-C H2 CHzCHzOHJ CHzCOO (3) N-CII:

CIIIIZEC% NC H: II 0 \CIIQCIIZOII CHzCOO (5) /N- lle vided into groupsconsisting of those given dewaxing, washing,

11 0 drying (at 60 C. for 20 minutes) and surface activating treat- H Bamerits; those given dewaxing, washing and drying (at 60 C. for 20minutes) treatments; and those given no precoating no (CHCHZNIUZHtreatment, and then an electrostatic coating was conducted on H20 00 2all sheets of these three groups. (6) N C H The coating apparatus usedhad an output of 200 cc/min., a diameter of 15 inches, a revolutionspeed of 1.500 r.p.m., and 01111330 10 a voltage capacity of 90 KV. Acoating consisting of commer- N CH Fe cial alkyd resin was applied ontothese sheets by the use of said a aratus 110 1 (CH CH CH 0 II pp 2 a) )2The results of the comparison of the coatabllity and the ad- CHSOZ 2hesiveness of the coatings between these three groups of 1 5 sheets areshown in the following table. The comparison of adwere prepared.Sheet-form moldings were then prepared by hesiveness was conducted byfirst forming, on the coated face mixing and kneading one of thesecompounds with of each sheet, 100 mesh-form checkered pattern consistingof acrylonitrile-butadiene-styrene copolymer, polystyrene or linesspaced at 1 mm. intervals, then placing a tape-form adhepolyethylene inan amount ranging from 0.5 to 2.0 percent by sive cellulose filmsthereon, and thereafter stripping the films weight of the weight of theresin. For comparison of the coataoff the sheet and comparing thecounted numbers of meshes bility and adhesiveness of the coatingsobtained, control sheetremaining on the sheets. Comparison ofcoatability was perform moldings (blank test pieces) not containing saidcomformed by observing the degrees of deposition of the coating poundswere also prepared. The respective sheets were dimaterial on the sheets.

Coated alter den'axing, washing, Coated after dedrying and Coatedwithout waxing, washing Surface Amount precoating and drying activatingof comtreatment treatments treatments Compound pound added Coat- Adhe-Coat- Adhe- Coat- Adhe- Resin number (percent) ability siveness abilitysiveness ability siveuess Blanktest. X A 0 0. 5 0 88 0 90 0 00 (1) 1. 00 .l-i 0 91 0 J6 2. 0 0 U5 0 97 0 100 0. 5 0 90 0 92 0 as (2) 1. 0 O 920 98 0 100 2. 0 (l 101] (l 100 l) 100 Acrylonitrile. butadiene- 0. 5 0J2 0 93 U 95 styrene eopolymer (3) 1. l) 0 92 l) O .1 2. o o as o 100 o100 o. 5 o 100 o 100 o 100 (1) 1. o o 100 o 100 o 100 2. o o 100 u 100 o101) o. 5 o on 0 or o 117 (5) 1. o 0 loo 0 on o no 2. o o 100 o 100 0too o. 5 u an u on 0 at o) 1. o 0 mo 11 as o 100 I 2. o o loo 0 ion 0ion (outed nller den'nxing, washing. (oated alter dedrying and (oatedwithout waxing. washing surface Amount preconling and drying activatingof comtreatment treatments treatments ompound pound added Coat- Adhe-Coat- Adhe- Coat- Adhe- Rvsm number (percent) ability siveness abilitysiveness ability siveness BlankteSt X A 47 0 76 0. 5 0 90 0 9-1 0 J6(1) 1. 0 O 92 0 95 0 U8 .2. 0 0 J7 l) 100 0 100 0. 5 0 06 0 100 0 100(2).. 1. o 0 100 o 100 o 100 2. o o 100 0 100 o 100 (a) o. 5 0 n4 o 95 o100 1.0 o 100 0 us 0 100 Polystym 2. 0 o 100 o 100 o 100 0. 5 0 or 0 970 95 (4) 1. 0 0 U3 0 J7 0 97 3. 0 0 U1) 0 9t) 0 100 0. 5 0 100 0 98 0100 (5) 1. 0 (l 100 t) 100 0 100 2. t) 0 100 0 100 0 100 0. 5 1] .I-l 0J8 0 J2 (6) 1. o o as o 100 o as 2. o o 100 o 100 u 100 X poor coatings.A Jalrly good coatings. 1) good eoatings.

Coated after dewaxing, washing,

Coated alter dedrying and Coated without waxing, washing surfaceprecoating and drying activating treatment treatments treatments Com-Amount pound added Coat- Adlle- Coat- Adhe- Coat- Adheltosin nuinbor(poi-cent) ability sivonoss ability siveness ability siveness Blank to XA 32 68 l). 0 84 0 U1 0 J8 (l) l). 7 0 JO 0 U4 0 100 1.0 0 .16 0 JO 0100 0.5 0 8i) 0 96 0 97 (2) 0. 7 0 J4 0 96 0 97 1.0 0 100 0 D9 0 100Polyethylenev 0. 5 0 J1 0 89 0 91 (6) 0. 7 0 U2 0 95 0 100 1. 0 0 92 0100 0 100 0. 5 0 100 0 99 0 98 (4) 0.7 0 100 O 100 0 J9 1.0 0 100 U 1000 100 0.5 0 100 0 100 0 100 (5) 0. 7 0 100 0 100 0 100 1. 0 0 100 U 1000 100 X=poor coatings. A=fairly good coatings. 0=g0od coatings.

As shown in the above table, by the application of the wherein:

method of the present invention, it is possible to perform a coatingcomparable to a coating of the prior art which includes the steps of thenamed precoating treatments, even when the precoating treatment, whichhas been indispensable with the conventional electrostatic coatingmethods, is omitted.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A method which comprises electrostatically applying a coatingmaterial to a molded object made of an electrostatically coatablesynthetic resin selected from the group consisting ofacrylonitrile-butadiene-styrene copolymers, acrylonitrile-styrenecopolymers, polystyrene, polyethylene, polypropylene, polyvinyl chlorideand polycarbonate, said resin containing admixed therein from about 0.1to about 5 percent by weight of the resin, of an amphoteric surfaceactive agent of the formula R is a hydrocarbon radical having seven-21carbon atoms,

R is selected from the group consisting of H and CH 2 is selected fromthe group consisting of -O- and M is a metal ion selected from the groupconsisting of Mg,

Ca, Zn, Ba and Fe,

R is selected from the group consisting of --R COO, R SO and R OSO(wherein R is selected from the group consisting of CH;, C H and -CH,,--

n is a number from O to 3.

2. A method according to claim 1, wherein said electrostatic coating isperformed on said article to be coated containing said amphotericsurface active agent, without giving said article a precoatingtreatment.

3. A method according to claim I, wherein said amphoteric surface activeagent is a compound in which R is a hydrocarbon radical containing from1 l to 17 carbon atoms.

4. A method according to claim 1, wherein said article to be coated isan acrylonitrile-butadiene-styrene copolymer.

5. A method according to claim 1, wherein said article to be coated ispolystyrene.

6. A method according to claim 1, wherein said article to be coated ispolyethylene.

2. A method according to claim 1, wherein said electrostatic coating isperformed on said article to be coated containing said amphotericsurface active agent, without giving said article a precoatingtreatment.
 3. A method according to claim 1, wherein said amphotericsurface active agent is a compound in which R is a hydrocarbon radicalcontaining from 11 to 17 carbon atoms.
 4. A method according to claim 1,wherein said aRticle to be coated is an acrylonitrile-butadiene-styrenecopolymer.
 5. A method according to claim 1, wherein said article to becoated is polystyrene.
 6. A method according to claim 1, wherein saidarticle to be coated is polyethylene.